SOMERVILLE, N.J. (AP)  A weapons expert testified Tuesday in the Jayson Williams manslaughter trial that tests of the retired NBA star's shotgun showed the weapon operated properly, firing only when the trigger was pressed and the safety was off.

The 12-gauge Browning double-barreled shotgun that killed van driver Costas "Gus" Christofi behaved as expected in eight different tests, some of which were repeated up to 10 times, said state police Detective Sgt. James Ryan.

The testimony sought to undercut a defense claim made during opening statements that the gun was prone to malfunction. The defense, which also maintains the shooting was an accident, is to begin cross-examination on Wednesday.

They may seek to explore an instance in which Ryan, demonstrating the tests to the jury (without live ammunition), said the weapon behaved differently than during the test.

The prosecution claims that Williams was reckless when he handled the shotgun after drinking with friends. Witnesses said he held it in one hand and snapped it shut, after which it fired. Christofi, 55, died within minutes of being hit with a single blast of 12 pellets.

Ryan also testified that:

_The end of the weapon was 3 feet or less from Christofi, but not directly against his chest, based on tests conducted with the Browning firing from various distances into material similar to his shirt. The noted forensic scientist Henry Lee testified Thursday that the muzzle was 6 inches to 18 inches from the victim.

Christofi, 55, was shot in the early hours of Feb. 14, 2002. Williams had gone with friends to see a Harlem Globetrotters game in Bethlehem, Pa., and Christofi had driven four Globetrotters from the game to a restaurant near Williams' estate for dinner with Williams and most of the group.

They then went to the mansion for an early morning tour, and Christofi was shot in Williams' bedroom, with three of the Globetrotters also in the room. All five shotguns and the rifle found in the bedroom were operable, Ryan said.

One Globetrotter, Benoit Benjamin, said he saw Williams pull the trigger; Globetrotter Chris Morris said Williams' hand was near the trigger; and Globetrotter Paul Gaffney had his back to Williams. A friend of Williams who said he was in the doorway, Kent Culuko, said Williams had a finger near the trigger.

In his opening statement last month, defense lawyer Billy Martin said they will present experts who will testify the shotgun cannot close with a finger on the trigger, and thus cannot fire. He also said it had no safety.

But Ryan demonstrated the safety, walking in front of the jury box while clicking it. The same lever also selected which barrel would fire first, he said.

Ryan described and demonstrated — with no live ammunition — the eight tests he conducted, including two in which he was able to close the gun, either slowly or with a snap, with light pressure on the trigger, leading it to fire immediately.

With heavy pressure on the trigger, the weapon would not close when he attempted to close it. Ryan explained that when the trigger was pressed hard, it pinched a locking bolt, preventing it from engaging and shutting the weapon.

The shotgun never fired when no finger was on the trigger and it was closed or snapped shut, nor did it fire when struck in different locations with a rubber mallet, Ryan said.

The jury also heard from a state police lab expert, Maureen M. Low-Beer, who said DNA taken from the shotgun grip was from several people, but not Christofi. She acknowledged that DNA could be removed by wiping.

Five witnesses have said that Williams wiped the gun, and four said he placed it in Christofi's hands. Three of those witnesses said that Culuko then wiped the gun again.

Williams is accused of manslaughter, charged with recklessly handling the shotgun, and also with attempting to cover up the shooting by trying to put Christofi's fingerprints on the gun and having others say that they were downstairs when Christofi shot himself.

Williams, 36, faces eight charges, including aggravated manslaughter and witness tampering, that could carry up to 55 years in prison. The least of the charges carries a penalty of up to 18 months in prison, but would likely result in probation.

Williams left the Nets after a decade in the NBA, unable to overcome a broken leg suffered a year earlier in a collision with a teammate. He was suspended from his job as an NBA analyst for NBC after the shooting.

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